Anvil for use in a high pressure apparatus

ABSTRACT

THE TOP SURFACE OF AN ANVIL UTILIZED IN A HIGH PRESSURE APPARATUS IS MADE TO FORM A CONVEXED CURVED SURFACE SO AS TO AVOID ANY BREAKAGE DUE TO BEING SHEARED OFF BY UTILIZING A COMPRESSION FORCE GENERATED IN THE ANVIL BY APPLYING A PRESSURE TO THE TOP SURFACE. A HIGH RATIO OF THE ACTUAL PRESSURE TO BE GENERATED IN THE CENTER OF THE SUBSTANCE TO BE PRESSURIZED TO THE MEAN PRESSURE TO BE APPLIED TO THE TOP SURFACE IS OBTAINED BY USING THE ANVIL.

March 16,1971 KAZUO YASUNAMI 3,570,963

ANVIL FOR USE IN A HIGH PRESSURE APPARATUS' Filed July 24, 1968 2 PRIOR ART O VENTOR Yuma MM BY Mam \PwL ATTORNEY United States Patent 3,570,063 ANVIL FOR USE IN A HIGH PRESSURE APPARATUS Kazuo Yasunami, Ashiya-shi, Japan, assignor to Kobe Steel Ltd., Wakinohama-cho, Fukiai-ku, Kobe, Japan Filed July 24, 1968, Ser. No. 747,188 Claims priority, application Japan, Aug. 1, 1967, 42/49,033 Int. 'Cl. 1530b 11/32 US. Cl. 18-165 1 Claim ABSTRACT OF THE DISCLOSURE The top surface of an anvil utilized in a high pressure apparatus is made to form a convexed curved surface so as to avoid any breakage due to being sheared off by utilizing a compression force generated in the anvil by applying a pressure to the top surface. A high ratio of the actual pressure to be generated in the center of the substance to be pressurized to the mean pressure to be applied to the top surface is obtained by using the anvil.

BACKGROUND OF THE INVENTION This invention relates to an anvil used in a high pres sure apparatus employed for the study of various properties of matter and for the purpose of synthesizing new materials by the conversion of the properties of matter.

The high pressure apparatus is herein defined as a device for pressurizing an object by the multi-face pressurizing method, including 4-face, 6-face, 8-face, etc.

The fundamental principle is to generate a high pressure in a substance of solid matter to be pressurized by pressurizing it by means of anvils.

The high pressure apparatus using, for instance, a 6- face pressurizing method is explained according to FIG. 1. Six anvils 1 which are conically shaped on the top surface and arranged slidably along the orthogonal three axes are moved forward by a suitable driving mechanism toward the substance M to be pressurized and placed in the center of the group of anvils 1 (pressurizing center) so that the substance M should be compressed, generating a high pressure therein.

This invention has improved the construction of the I anvil regardless of the pressurizing method such as the 6-face pressurizing method shown in FIG. 1 and the like.

Formerly, anvils 1 used in this type of high pressure apparatus have the shape of a frustum with a top surface 2 formed as shown in FIG. 2 and top surface 2 is a plane placed perpendicular to the center axis of the anvil. According to experiences, the defects of conventional anvils 1 are that while they are used to generate a high pressure of about 100,000 atmospheric pressure, cracks will appear on the top surface which will develop into breakage. Since the anvils are expensive, the economical losses incurred are immense.

Another weak point of the anvils is that it is impossible to increase their pressurizing eificiency over a certain limit. (The pressurizing efficiency referred to here means the ratio of the actual pressure P generated in the center of the substance to be pressurized to the imaginary mean pressure R applied to the top surface of the anvil. The imaginary means pressure means the actual load applied to the anvil divided by the area of the top surface of the anvil. The reason why a word imaginary is used is that the actual load is applied to not only the top surface but also the gasket part at the side of the anvil. Therefore, the imaginary mean pressure is substantially larger than the actual mean pressure.)

This invention has been accomplished in the following ice manner after making investigation on the causes of the above defects.

(1)As stated above, the anvils generally are subject to a large compressive load. Previously, therefore, materials having high compression strength such as tungsten carbide (compressive strength of 500 kg./cm. to 600 kg./cm. and tensile strength of kg./cm. have been mainly used, but they are very expensive.

With conventional anvils, top surface 2 is deformed during the pressurizing operation into a concave form as shown by chain line 2' in FIG. 2. This fact can be clearly observed by measuring the outer shape of the substance M after compression. This tendency becomes more conspicuous as the substance to be pressurized increases in volume, that is to say, as the top surface of the anvil becomes larger.

As a result, it is considered that a tensile stress at acts in a tangential direction substantially within and near top surface 2 of the anvil and as the tensile strength of the substance is comparatively small, although it has a large compressive strength as described above, cracks appear from near top surface 2 of the anvil and will finally develop to break the anvil.

(2) Further, with conventional anvils the distortion strain occurred in the center axes of the substance by the movement of the anvils during the pressurizing operation owing to the deformation stated in the above section (1), is less than the distortion strain in the outer side, with each surface of the substance. Consequently, as shown by curved chain line A in FIG. 5, there is a tendency that the pressure generated in the substance M is minimum at the pressurizing center 0 and becomes larger as the positions approach the two outer sides.

This means that it is impossible in the conventional anvil to concentrate the pressurizing force to the pressurizing center when the pressurizing operation of the substance is finally finished by means of the movement of the anvil, and, therefore, to improve over a certain limit the pressurizing efficiency which is the ratio of the actual pressure P generated in the pressurizing center to the mean pressure P applied to the top surface.

SUMMARY OF THE INVENTION It is a characteristic feature of this invention to have the top surface of the anvil formed in a convexed curved surface.

According to various experiments conducted by this inventor, it has been confirmed that this anvil is capable of preventing breakages such as encountered before and of increasing the pressurizing efiiciency.

An object of this invention is to provide anvils of high safety which are almost free of breakage.

A further object of this invention is to provide anvils which generate higher pressure with the same compression stroke.

A still further object of this invention is to provide anvils which are capable of obtaining the higher pressure at higher pressurizing efficiencies.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the principle of a very high pressure apparatus based on a 6-face pressurizing system,

FIG. 2 is a partially sectioned front view of a conventional a-nvil used in the above system,

FIG. 3 is a partially sectioned front view of an anvil of this invention,

FIG. 4 is a top plan view of the anvil of this invention, and

FIG. 5 is a diagram showing the distributions of pressure in the anvils.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 3 and 4, a top surface 20 of an anvil 10 is formed in a convexed curved surface. The convexed curved surface referred to above means any kind of surfaces having one or more radii of curvature, such as, a part of a sphere, ellipsoid, paraboloid, etc. The deformation of top surface 20 of anvil 10 is explained as follows:

When top surface 20 is subject to a pressure in a direction vertical to it, the surface will be deformed into the state shown by chain line 20' of FIG. 3.

In this case, as a compressive stress ac will work on top surface 20 tangentially to the top surface of the anvil, generation of cracks is prevented, whereas in the conventional technique a tensile stress works on the top surface.

Moreover, when anvil 10 is used, the distortion strain occurred in the center axis of the substance by the movement of the anvil is larger than the distortion strain in the conventional method, with each surface of the substance.

Accordingly, as shown by solid curved line B of FIG. 5, the distribution of the actual pressure P becomes in its maximum value at the pressurizing center which is larger than the conventional actual pressure P As a result, the pressurizing efficiency P /P will improve. More particularly, as top surface 2 of anvil is made to form a convexed curved surface, under the same compression stroke, the volume diminish of the substance to be pressurized of subject invention is larger than that obtained in the conventional technique. This means that the volumetric stress of the whole substance using the subject invention is larger than that using the conventional technique so that a higher pressure can be obtained by using the anvil of the subject invention.

According to the result of an example of an experiment of the 6-face pressurizing method, it has been found that a very good result can be obtained when a spherical surface is employed the radius of curvature R of which is approximately 2L(R2L) as against the diagonal length L (FIG. 4) of top surface of anvil 10.

The outline of the result is that a pressure of about 100,000 atmospheric pressure could be generated in 21 substance to be pressurized having an 8-cc. volume without damage to the anvils, attaining an efficiency of about 80%. In such a case, it is impossible with conventional type anvils to produce a pressure of about 100,000 atmospheric pressure due to the breakage of the anvils and the efiiciency is observed to be about Thus, this invention Which provides an anvil which can be expected to reduce the danger of breakage of large type anvils and increase their efficiency is considered to be helpful in applying larger type anvils to practical use to meet the recent demand for larger types of very high pressure generators in the fields of both research and production.

If the top surface area of the anvil becomes larger as the anvil increases in size, the defects inherent with conventional anvils will become all the more conspicuous. But, according to this invention, it is possible to easily manufacture a high pressure generator of a large size and high pressurizing efiiciency without receiving any restrictions from the strength of the anvil and the practical effectiveness of the invention is remarkable.

What is claimed is:

1. An anvil for use in an apparatus for generating a high pressure in four or more perpendicular directions characterized in that the top surface of the anvil is composed of an integral convexed curved surface with a radius of curvature substantially twice the diagonal length of the top of the anvil and that the center of curvature is on the axial center line of the anvil.

References Cited UNITED STATES PATENTS 1,911,775 5/1933 Smithetal. 2,941,245 6/1960 Cheney. 3,150,413 9/1964 Zectlinetal. 3,440,687 4/1969 Hall. 3,453,687 7/1969 Young.

FOREIGN PATENTS 1,457,690 9/1966 France.

WILLIAM S. LAWSON, Primary Examiner 

